NAME

       sd_get_seats, sd_get_sessions, sd_get_uids, sd_get_machine_names - Determine available
       seats, sessions, logged in users and virtual machines/containers

SYNOPSIS

       #include <systemd/sd-login.h>

       int sd_get_seats(char ***seats);

       int sd_get_sessions(char ***sessions);

       int sd_get_uids(uid_t **users);

       int sd_get_machine_names(char ***machines);

DESCRIPTION

       sd_get_seats() may be used to determine all currently available local seats. Returns the
       number of seat identifiers and if the input pointer is non-NULL, a NULL-terminated array
       of seat identifiers is stored at the address. The returned array and all strings it
       references need to be freed with the libc free(3) call after use. Note that instead of an
       empty array NULL may be returned and should be considered equivalent to an empty array.

       Similarly, sd_get_sessions() may be used to determine all current login sessions.

       Similarly, sd_get_uids() may be used to determine all Unix users who currently have login
       sessions.

       Similarly, sd_get_machine_names() may be used to determine all current virtual machines
       and containers on the system.

       Note that the returned lists are not sorted and in an undefined order.

RETURN VALUE

       On success, sd_get_seats(), sd_get_sessions(), sd_get_uids() and sd_get_machine_names()
       return the number of entries in the arrays. On failure, these calls return a negative
       errno-style error code.

   Errors
       Returned errors may indicate the following problems:

       -ENOMEM
           Memory allocation failed.

NOTES

       Functions described here are available as a shared library, which can be compiled against
       and linked to with the libsystemd pkg-config(1) file.

       The code described here uses getenv(3), which is declared to be not multi-thread-safe.
       This means that the code calling the functions described here must not call setenv(3) from
       a parallel thread. It is recommended to only do calls to setenv() from an early phase of
       the program when no other threads have been started.

HISTORY

       sd_get_machine_names() was added in version 203.

SEE ALSO

       systemd(1), sd-login(3), sd_session_get_seat(3)